Composite beam

ABSTRACT

A structural beam has a thin metal web with a plurality of holes located along its top and bottom edges. One or more rectangular flange pieces are located on each side of the web overlying its top margin and one or more rectangular flange pieces are located on each side of the web overlying its bottom margin. The flange pieces contain holes which are aligned with the holes in the web piece and fasteners extend through the aligned holes to fasten the flange pieces to the web.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to a structural beam and, in particular, to astructural beam that is a composite of metal and wood elements.

Light commercial and industrial structures, such as warehouses, areoften constructed as wood frame structures in order to reduce the cost.Several types of large wood beams (24 inches to 4 feet high) are usedfor this purpose. The least costly of these beams are gluelam beams.Gluelam beams are well known and widely used but are dimensionallyunstable. The larger the beam, the more this dimensional instabilitybecomes a problem. At the other end of the spectrum, parallel strandlumber beams are very dimensionally stable, but their cost approachesthat of steel beams. While the overall cost of constructing a buildingusing parallel strand lumber beams is less than using steel beams, otheradvantages of steel often outweigh this relatively minor costdifferential and large parallel strand lumber beams have not been widelyused in light commercial and industrial buildings.

The subject invention provides a composite wood/steel beam having a costwhich is compatible with gluelam beams and yet has the dimensionalstability of parallel strand beams, or even steel beams. This isaccomplished by providing a planer steel web with wood top and bottomflange pieces, which are separate from the web and from one another. Thetop and bottom flange pieces are attached to the top and bottom edges ofthe web respectively, with one top and bottom flange piece being on eachside of the web.

The foregoing and other objectives, features, and advantages of theinvention will be more readily understood upon consideration of thefollowing detailed description of the invention, taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a foreshortened perspective view showing a beam embodying thesubject invention.

FIG. 2 is a cross-sectional view, at an enlarged scale, taken along theline 2-2 of FIG. 1.

FIG. 3 is a detail view, at an enlarged scale, of an alternativeembodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1 and 2 of the drawings, a beam 10 includes aplaner web 12, the web 12 is preferably made from an elongate thin pieceof a relatively high-strength metal, such as steel, however it can beany material that will withstand the load that will be transmitted tothe resulting beam. The web has a length which is substantially equal tothe desired length of the beam and a height which is substantially equalto the desired height of the beam. The thickness of the web depends onthe size of the beam and the load it is intended to carry, but it isrelatively thin.

Located respectively at the top and bottom edges of the web are flanges14 a and 15 b. The flanges are separate from the web and separate flangepieces 16 are located on each side of the web. A plurality of holes 18extend through the web at spaced apart intervals along its upper andlower margins. A plurality of similar holes 20 extend through the flangepieces 16, and the holes 20 are aligned with the holes 18 when theflange pieces overlie the top and bottom margins of the web.Counterbores 22 are aligned with the holes 20 at the outside of eachflange piece. Fasteners 24 extend through the holes 18 and 20 to securethe flange pieces to the web. In the embodiment illustrated, thefasteners 24 are bolts 26 which have heads 28 that fit within thecounterbores at one side of the beam, and nuts 30 which fit within thecounterbores at the other side of the beam.

The flange pieces preferably are made from a material that nails can bedriven into, in order that the resulting beam can easily be utilized inconjunction with other wood elements. The flange pieces ideally areparallel strand lumber in order to also provide a high level ofdimensional stability. High dimensional stability is particularlyimportant where the flange pieces are separate from the web and attachedto the web with fasteners because shrinkage of the flange pieces wouldcause their connection to the web to become loose. Alternatively, theflange pieces could be other wood products that have a reasonable levelof dimensional stability or even simply be dimension lumber. The size ofthe flange pieces depends upon the size of the beam and the intendedload. A representative beam, which would be used for roof or floorjoists in a building, would have a web thickness of ⅛ inch to ½ inch, aweb height of 1-4 feet and the flange pieces would be 3½ inches wide. Ifit is necessary to have flanges which are larger than are available inone piece of lumber, multiple flange pieces 16 can be placed on eachside of the web, FIG. 3.

The web 12 preferably will have central openings 32 located in it whichwill allow wire, cables, pipes and the like to be easily passed throughthe beam. The size, shape, location and number of openings will dependon the intended use of the beam, and a simple circular opening is shownin the drawing for illustration purposes. The openings 32 and the holes18 can be formed in the web in a single operation by stamping.

Due to its use of common, readily available materials, the beam of thesubject invention is quickly and easily fabricated without requiringcostly tooling or equipment. The beam of the subject invention providesthe nailability and dimensional stability of a parallel strand lumberbeam at a far lower cost than a beam made entirely of this material,and, in addition, provides performance which is comparable to metalbeams.

The terms and expressions which have been employed in the foregoingspecification are used therein as terms of description and not oflimitation, and there is no intention, in the use of such terms andexpressions, of excluding equivalents of the features shown anddescribed or portions thereof, it being recognized that the scope of theinvention is defined and limited only by the claims which follow.

1. A beam for supporting a structural load comprising: (a) A planer webhaving a top edge, a bottom edge, a length and a thickness; (b) said webdefining a plurality of holes proximate its top edge and a plurality ofholes proximate its bottom edge; (c) at least two rectangular top flangepieces which are separated from said web, one of said top flange piecesbeing located on each side of said web adjacent said top edge; (d) saidtop flange pieces defining a plurality of holes which are aligned withthe holes in said web proximate said top edge; (e) a plurality offasteners which extend through the holes in said top flange pieces andthe holes in said web proximate said top edge and secure said top flangepieces to said web; (f) at least two rectangular bottom flange pieceswhich are separated from said web, one of said top flange pieces beinglocated on each side of said web adjacent said bottom edge; (g) saidbottom flange pieces defining a plurality of holes which are alignedwith the holes in said web proximate said top edge; and (h) a pluralityof fasteners which extend through the holes in said bottom flange piecesand the holes in said web proximately said bottom edge and secure saidbottom flange pieces to said web.
 2. The beam of claim 1 wherein saidweb is a thin metal sheet.
 3. The beam of claim 2 wherein said web has athickness of between ⅛ inch and ½ inch.
 4. The beam of claim 3 whereinsaid web has a height between 1 foot and 4 feet.
 5. The beam of claim 1wherein said top and bottom flange pieces are parallel strand lumber. 6.The beam of claim 1 wherein said top and bottom flange pieces aredimension lumber.
 7. The beam of claim 1 wherein there is one of saidtop and bottom flange pieces on each side of said web.
 8. The beam ofclaim 1 wherein there are more than one of said top and bottom flangepieces on each side of said web.
 9. The beam of claim 1 wherein theholes in said top and bottom flange pieces contain counterbores.
 10. Thebeam of claim 1 wherein said fasteners comprise bolts having heads whichfit in the counterbores on the flange pieces on one side of said web andnuts which fit in the counterbores on the flange pieces on the otherside of said web.
 11. The beam of claim 1 where at least one hole isdefined in said web between said top and bottom flange pieces.